A wide variety of food products contain introduced gas, such as air, nitrogen and/or carbon dioxide. Typically, aerated food products tend to be of a relatively neutral pH—approximately pH 6.0 to 7.5. Examples of such products include ice cream, whipped toppings and whipped cream.
Most aerated food products comprise proteins and these are essential for both the incorporation of air bubbles and their subsequent stability. However, dairy proteins in particular tend to be pH sensitive. That is, their charge, interactions, and their conformation, can alter as a function of pH. This adversely affects both the foaming ability and the resulting stability of the foams made using protein, particularly for aerated products of pH 5.4 and lower. This is because both the surface activity and the solubility of many proteins are reduced as pH is lowered. For example, sodium caseinate precipitates at about pH 4.6 to 4.8. This results in both poor air incorporation and resulting instability of aerated products.
This fact has been described extensively in the literature and producing stable foams at low pH is a known problem. However, although there are routes described in the art that facilitate the formation of aerated food products at low pH, they tend to have limitations. Such limitations are overcome by the current invention. For example, gelatine is often added as a stabiliser which both thickens the product and also aids in air stability. Most “mousse” products take advantage of the use of gelatine. However, gelatine is an animal based stabiliser which is not seen as a suitable ingredient by many consumers. Furthermore, use of gelatine usually means that the product will be “set”, i.e. will not flow. This means one is limited to the type of products that can be made using this formulation technology.
Other methods take advantage of other chemical emulsifier systems such as sucrose esters and/or variants of mono-/di-glycerides of saturated fatty acids. Although these non-dairy based formulation technologies will form aeratable products at low pH, often significant quantities of emulsifier are required for long term stability (in excess of 3 weeks). This can have an undesirable influence on both taste and texture. Furthermore, significant quantities of chemical emulsifier in foods are not acceptable to the consumer.
Ideally, a suitable aerating agent would be pH insensitive (in terms of its foaming behaviour), be functional at low concentrations such that no undesirable impact on taste and texture was apparent, and could be used to form aerated foods where the foam was stable in excess of 3 weeks at chill or ambient temperature.